From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.5 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39803C433DB for ; Sat, 9 Jan 2021 21:56:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F0C2723AC0 for ; Sat, 9 Jan 2021 21:56:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726154AbhAIV4R (ORCPT ); Sat, 9 Jan 2021 16:56:17 -0500 Received: from mail.kernel.org ([198.145.29.99]:39418 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726141AbhAIV4R (ORCPT ); Sat, 9 Jan 2021 16:56:17 -0500 Received: from archlinux (cpc108967-cmbg20-2-0-cust86.5-4.cable.virginm.net [81.101.6.87]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EBF3C23AC0; Sat, 9 Jan 2021 21:55:34 +0000 (UTC) Date: Sat, 9 Jan 2021 21:55:30 +0000 From: Jonathan Cameron To: Gwendal Grignou Cc: lars@metafoo.de, andy.shevchenko@gmail.com, linux-iio@vger.kernel.org Subject: Re: [PATCH v2] iio: hrtimer: Allow sub Hz granularity Message-ID: <20210109215530.0ab8950a@archlinux> In-Reply-To: <20201213170228.745bcd48@archlinux> References: <20201209224644.185134-1-gwendal@chromium.org> <20201213170228.745bcd48@archlinux> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org On Sun, 13 Dec 2020 17:02:28 +0000 Jonathan Cameron wrote: > On Wed, 9 Dec 2020 14:46:44 -0800 > Gwendal Grignou wrote: > > > Allow setting frequency below 1Hz or sub 1Hz precision. > > Useful for slow sensors like ALS. > > > > Test frequency is set properly: > > modprobe iio-trig-hrtimer && \ > > mkdir /sys/kernel/config/iio/triggers/hrtimer/t1 && \ > > cd /sys/bus/iio/devices/triggerX ; > > for i in 1 .1 .01 .001 ; do > > echo $i > sampling_frequency > > cat sampling_frequency > > done > > > > Signed-off-by: Gwendal Grignou > Just to note as Andy raised the ABI docs question. > The attribute this is providing is more generic than just for the hrtimer > trigger and as such is in the main ABI docs. The reason is that > samping_frequency is able to occur in various different places depending > on where it has side effects. In particular a dataready trigger for > a device with variable sampling frequency will usually be in the > iio:\deviceX directory because it will have affects on anti aliasing filters > so has an impact even if you are just reading from sysfs. > We could add specific docs for this case (though because all ABI docs > for a given named attribute need to be in one file, it would be rather > messy). > > Applied to the togreg branch of iio.git and pushed out as testing > for the autobuilders to see if we missed anything. > > Thanks, > > Jonathan > > > > --- > > Changes since v1: > > - Added documentation. > > > > Documentation/iio/iio_configfs.rst | 1 + > > drivers/iio/trigger/iio-trig-hrtimer.c | 25 +++++++++++++++---------- > > 2 files changed, 16 insertions(+), 10 deletions(-) > > > > diff --git a/Documentation/iio/iio_configfs.rst b/Documentation/iio/iio_configfs.rst > > index ecbfdb3afef7e..428419f8732c4 100644 > > --- a/Documentation/iio/iio_configfs.rst > > +++ b/Documentation/iio/iio_configfs.rst > > @@ -99,3 +99,4 @@ Each trigger can have one or more attributes specific to the trigger type. > > > > "hrtimer" trigger type doesn't have any configurable attribute from /config dir. > > It does introduce the sampling_frequency attribute to trigger directory. > > +That attribute sets the polling frequency in Hz, with mHz precision. > > diff --git a/drivers/iio/trigger/iio-trig-hrtimer.c b/drivers/iio/trigger/iio-trig-hrtimer.c > > index a5e670726717f..06acd6dc79a8c 100644 > > --- a/drivers/iio/trigger/iio-trig-hrtimer.c > > +++ b/drivers/iio/trigger/iio-trig-hrtimer.c > > @@ -22,7 +22,7 @@ > > struct iio_hrtimer_info { > > struct iio_sw_trigger swt; > > struct hrtimer timer; > > - unsigned long sampling_frequency; > > + int sampling_frequency[2]; > > ktime_t period; > > }; > > > > @@ -38,7 +38,9 @@ ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev, > > struct iio_trigger *trig = to_iio_trigger(dev); > > struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig); > > > > - return snprintf(buf, PAGE_SIZE, "%lu\n", info->sampling_frequency); > > + return iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO, > > + ARRAY_SIZE(info->sampling_frequency), > > + info->sampling_frequency); > > } > > > > static > > @@ -48,18 +50,21 @@ ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev, > > { > > struct iio_trigger *trig = to_iio_trigger(dev); > > struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig); > > - unsigned long val; > > - int ret; > > + unsigned long long val; > > + int integer, fract, ret; > > > > - ret = kstrtoul(buf, 10, &val); > > + ret = iio_str_to_fixpoint(buf, 100, &integer, &fract); > > if (ret) > > return ret; > > > > - if (!val || val > NSEC_PER_SEC) > > + val = fract + 1000 * integer; > > + > > + if (!val || val > NSEC_PER_SEC * 1000) > > return -EINVAL; > > > > - info->sampling_frequency = val; > > - info->period = NSEC_PER_SEC / val; > > + info->sampling_frequency[0] = integer; > > + info->sampling_frequency[1] = fract * 1000; > > + info->period = NSEC_PER_SEC * 1000 / val; 0 day pointed out this is a 64 bit division so needs to work on 32 bit platforms. I've dropped it for now, please respin with that fixed up. Thanks, Jonathan > > > > return len; > > } > > @@ -135,8 +140,8 @@ static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name) > > hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); > > trig_info->timer.function = iio_hrtimer_trig_handler; > > > > - trig_info->sampling_frequency = HRTIMER_DEFAULT_SAMPLING_FREQUENCY; > > - trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency; > > + trig_info->sampling_frequency[0] = HRTIMER_DEFAULT_SAMPLING_FREQUENCY; > > + trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency[0]; > > > > ret = iio_trigger_register(trig_info->swt.trigger); > > if (ret) >